Flood Detector
Introduction:
Last week I
had a big flood in my house. A water tube broke in the middle of the night
making lots of damage. Wooden floor, furniture, small electronic appliances,
all damaged due to the water. This made me think on a project that would sense
water on the floor and trigger an alarm.
The
detector should be able to sense water and trigger an alarm. Also it should be
small and battery operated. Battery ’s voltage
should be checked also.
Schematic:
Part
List:
R1 10K ohms resistor
R2 10K ohms resistor
R3 10K ohms resistor
R4 1K ohms
resistor
R5 10K ohms
resistor
R6 1K ohms
resistor
C1 100nF cap
Led1 5mm green led
Led2 5mm red led
D1 4V7 zener diode
Piezo Piezo HPE-120
VR1 78L05 regulator
IC1 12F683 SOIC microcontroller from Microchip
S1 Push button
Others:
Box
9V battery clip
PCB
Metal strips
Hex program for the
microcontroller
PCB:
The PCB used for this Project is
single layer and its size is 27.02
mm x 32.41mm.
The SOIC version of the
microcontroller helps to reduce the size of the PCB.
Top
Side
Here is the top view with the
components
Bottom
Side
Box
and probes:
I tried to find a small box that
would fit both circuit and box. This way it would be more discrete.
The box that I used did not had enough room
for all components, so I had to place both leds and piezo on the exterior of
the box. That detail didn’t make any difference since the leds should stay
visible and the piezo free to make the loudest sound possible.
The probes can be made from any
conductive material, but I preferred not to use copper because it deteriorates
with time. In my opinion a good material to be used is stainless steel or
aluminium. However, maintenance should be done from time to time checking the
probes and testing them with water.
Also, the probes should be placed
not to far apart from each other and they never should touch each other. The
more probe area available for water sensing the better.
The probes I used in my project
are made from aluminium.
The final
assembly looks like this:
The
detector is placed on the floor. It’s possible to use some double side tape and
stick the detector against the wall or just leave it like the picture below.
The probes are on the bottom of the box touching the floor and the leds on the
top
Hex
Program:
The Hex
program must be saved in the microcontroller’s memory before soldering on the
PCB.
Testing:
Turning on
the circuit, both leds and piezo are tested. Also the probes are checked. If
the probes are sensing water or any kind of leakage it will turn on the red led
and it will trigger the piezo.
After everything
is checked ok the detector will enter it’s normal state.
Every 10
seconds it will check the probes and the battery’s voltage.
If water
gets between the probes the detector will enter the alarm mode where the red
led will turn on and the piezo will start making a loud sound. The detector
will keep itself in alarm mode until S1 is pressed.
If the
battery’s voltage is good, the green led will flash every 10 seconds but if the
voltage reaches 7V the red led will flash every 10 seconds and the piezo will
make a short sound to indicate it’s time to change the battery.
The water
detection time is less than 10 seconds. Since the microcontroller enters a low
consumption state between readings to preserve battery life, this state is
always 10 seconds long. If water reaches the probes while being in the low
power state it will have to wait until it finishes the sleep state before it
can trigger the alarm.
Conclusion:
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2 Respones to "Flood Detector"
Yeah.. It is really useful I think. You have a nice post. Thank you very much for sharing
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